Decreased airway narrowing and smooth muscle contraction in hyperresponsive pigs

smooth muscle contraction in hyperresponsive pigs. J Appl Physiol 93: 1296–1300, 2002. First published June 21, 2002; 10.1152/japplphysiol.00150.2002.—Increased smooth muscle contractility or reduced smooth muscle mechanical loads could account for the excessive airway narrowing and hyper-responsiveness seen in asthma. These mechanisms were in-vestigated by using an allergen-induced porcine model of airway hyperresponsiveness. Airway narrowing to electric field stimulation was measured in isolated bronchial seg-ments, over a range of transmural pressures (0–20 cmH2O). Contractile responses to ACh were measured in bronchial segments and in isolated tracheal smooth muscle strips iso-lated from control and test (ovalbumin sensitized and chal-lenged) pigs. Test airways narrowed less than controls (P 0.0001). Test pigs showed reduced contractility to ACh, bot